From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clinton Lee Taylor Subject: Re: [PATCH] barrier support for other md/raid levels Date: Sun, 20 Sep 2009 23:48:42 +0200 Message-ID: References: <19123.9980.940255.937839@notabene.brown> <4AB372BA.6020101@redhat.com> <4D87015385157D4285D56CA6101072FF26C2CCB1@exchange07.valvesoftware.com> <4AB3D148.3060607@redhat.com> <87f94c370909181138g197be2fegd4032778ca6d3351@mail.gmail.com> <4AB3D4C8.1080602@redhat.com> <70ed7c3e0909181318v879ab30h5ffdf8e0b57799b4@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <70ed7c3e0909181318v879ab30h5ffdf8e0b57799b4@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: "Majed B." Cc: "linux-raid@vger.kernel.org" List-Id: linux-raid.ids Greetings ... 2009/9/18 Majed B. : > For what it's worth, I use XFS on one of my arrays, and whenever > mounting it, I get this error: > > [ 2212.567725] Filesystem "dm-0": Disabling barriers, trial barrier write failed > > So I guess you could use XFS to run your tests. I saw this meesage today, and remember both this thread and that on my CentOS 5.4, which I have moved a RAID5/ext4 filesystem from a Fedora 10 ... I'm getting these reports in my message log ... Sep 19 14:59:52 zeus kernel: JBD: barrier-based sync failed on md5 - disabling barriers Sep 19 15:06:12 zeus kernel: EXT4-fs: barriers enabled Would this help with testing? >>>>> >>>>> It seems like what you'd need to robustly test barriers is some sort of >>>>> barrier-supporting loopback device, which >>>>> acted correctly with barriers, but had worst-case behavior without them >>>>> (buffering things for random arbitrarily long periods of time, >>>>> performing all operations in random order, etc). Best of luck ... Thanks Mailed LeeT